New Moon

There is one thing about New Moon costars Robert Pattinson and Kristen Stewart that is undeniable – their attraction to one another is palpable.

"The chemistry is incredible," says costar Ashley Greene, who joined the duo at Comic-Con in San Diego to promote their new flick in the Twilight series.

Pattinson, 23, and Stewart, 19, reunited Thursday at the convention after spending most of the summer on different coasts: she in L.A. filming The Runaways (portraying rocker Joan Jett); he in New York City shooting the indie drama Remember Me.

"They're just people you can feel like you can relate to," says New Moon screenwriter Melissa Rosenberg. "That sets them apart in a lot of ways."

Rosenberg also praised the two as "genuine." The costars start filming Eclipse, the third Twilight feature, in August.

Twilight fans are used to the renegade vampire Victoria causing trouble for lovers Bella and Edward, but come the third installment of the film series, they may be taken aback by Bryce Dallas Howard baring her fangs in the role.

That's right: The 28-year-old daughter of director Ron Howard will be replacing Rachelle Lefevre, 30, who took on the role for the first film and its upcoming sequel, New Moon.

"Rachelle brought Victoria to great screen life, and Bryce will bring a new dimension to the character,"says Erik Feig, president of worldwide production and acquisitions for Summit Entertainment. "The franchise is lucky to have such a talented actress as Bryce coming in to fill the role."

According to Summit, Lefevre is leaving the series because of scheduling conflicts with a new film project. She's slated to appear opposite Dustin Hoffman in the independent film Barney's Version, which begins filming the same day as Eclipse – only on the opposite end of the continent, in Quebec